We have isolated zebrafish homolog genes for CBFA2, CBFB, and C/EBP1-4. The CBFA2 and CBFB genes are involved in leukemogenesis and the control of early hematopoiesis in mammals. C/EBP genes are involved in the control of myeloid differentiation and maturation. We have analyzed the sequence conservation of these zebrafish genes, and determined their expression patterns during embryogenesis by RNA in situ hybridization. The CBF genes and C/EBP genes appear to be expressed in similar patterns as their mammalian counterparts. Promoter-green fluorescent protein constructs will be generated which allow us to study gene expression in live embryos. The functional role of these genes during embryogenesis will be assessed by microinjection of cDNA, RNA, and oligo constructs into embryos. Finally, the potential involvement of these genes in fish mutants with defects in embryogenesis will be analyzed using genome analysis tools.